Presses for cutting blanks from sheet material



April 9, 1957 F. SEABURY n ETAL 2,788,070

PRESSEIS FOR CUTTING BLANKS FROM swam MATERIAL Filed Feb. 11. 1954PRESSES FOR CUTTING BLANKS FROM SHEET MATERIAL Application February 11,1954, Serial No. 409,670

14 Claims. (Cl. 164-23) This invention relates to presses and moreparticularly to presses of the type commonly known as clicking machines,for use in cutting blanks from sheet material.

In clicking machines as heretofore constructed, there is provided acutting bed, a beam or platen mounted upon a spindle at one side of thebed for movement across the cutting bed and arranged for reciprocationby power means toward and away from the bed for forcing a freely movablecutting die through the sheet material supported upon the bed in orderto produce blanks. The cutting bed usually comprises a block of wood ora pad of rubber or other material which is rigid enough to support thesheet material against pressure applied by the platen, and, at the sametime is penetrable by the cutting dies used so that the dies can beforced through the sheet material and into the block or pad a sufficientdistance to insure a complete penetration of the material in producingblanks.

One ditficulty which has been experienced, heretofore, is that theplaten must be adjusted to a height above the cutting bed in its restposition for a given length of stroke so that upon operation of theplaten the die will be forced completely through the material and intothe block and at the same time will not penetrate the block to such anextent that the die will stick. Improper adjustment of the height of theplaten for a particular length of stroke thus may result in the slowingof the cutting operations because of the necessity of prying a stuck diefrom the block. Deep penetration of the block also increases the wearthereof and frequently results in unsatisfactory cutting because of theforcing of the material into the block itself. On the other hand, if theplaten does not move downwardly far enough the die will not becompletely driven through the material resulting in incompleteseparation of the blank from the material or in blanks having raggededges.

In view of the foregoing, it is an object of the invention to provide animproved press, of the type referred to, in which the stroke of theplaten is automatically controlled independently of the thickness of thematerial operated upon or the height of the dies used.

To this end and as shown there is provided a press in which there are awork support and a platen constructed and arranged for relative movementtoward and away from each other in performing pressure applyingoperations upon sheet material, carried by the work support, to produceblanks by means of a die located between the work support and platen,together with means for effecting relative movement of the work supportand platen. toward each other, and means responsive to engagement of thedie with the work support for arresting the relative move ment of thework support and platen toward each other.

Preferably, and as shown, the work support comprises a cutting blockhaving an electrically conductive portion and there are provided powermeans, for effecting relative movement of the work support and platen,controlled byan electric circuit which includes the work support. Asshown, the platen is actuated by hydraulic mechanism nited States PatentFf I I 1 Ce 2,788,070

. including a solenoid operated valve for controlling the direction ofthe flow of fluid to act upon a piston connected to a spindle upon whichthe platen is mounted. Preferably too, the solenoid is controlled bymeans of an electric circuit which passes through the platen, die, and

. the coductive block, so constructed and arranged that the thickness ofthe work or the height of the die.

Preferably, and as shown, the control circuit includes time delayelements whereby the action of the solenoid can be delayed sufficientlyso that the platen will be effective to force the die a short distanceinto the block before movement of the platen away from the block iscommenced. Thus the depth of penetration of the die can be adjusted fordifferent kinds of work, or cutting blocks, or dies, if necessary, butonce adjustment has been made for a particular run of blanks of giventhickness, size, and material, no further adjustment of the machine isrequired. In this connection it is to be noted that if dies of differentheights are used no adjustment of the height of the platen relatively tothe block is necessitated. Furthermore, since penetration of the dieinto the block is closely controlled the block is not subjected toexcessive wear and its life is considerably increased.

These and other features of the invention are disclosed in the followingspecification and the accompanying drawings and are pointed out in theclaims.

In the drawings,

Fig. 1 is a side elevation, partly in section, of a portion of a pressembodying one form of my invention and includes a diagrammatic viewshowing a solenoid valve control mechanism and an electric circuittherefor; and

Fig. 2 is a vertical cross section on an enlarged scale through aportion of the machine illustrating the relation of the work support tothe die and work supported thereon.

The illustrated machine comprises a work support in the form of acutting bed 10, Fig. l, for supporting sheet material such as leather12, cloth, paper, metal foil, or other material, to be operated upon bya freely movable die 14 to produce blanks. The die is forced through thematerial by a platen or beam 16 mounted upon a vertical spindle 18 atone side of the bed for swinging movement across the bed into operativeposition over the die and arranged for reciprocation toward and awayfrom the bed in a pressure. applying operation upon the die.

The platen is preferably reciprocated by hydraulic power means. To thisend, the lower portion of the spindle 18 carries a piston 20 slidablymounted in a cylinder 22 having fluid passages 24 and 26 connectingupper and lower portions of the interior of the cylinder above and belowthe piston to a valve casing 28. The interior of the casing is connectedto upper and lower fluid inlet passages 30 and 32 extending to a fluidsupply source 34. The central portion of the valve casing is providedwith a fluid exhaust passage 36. Within the valve casing is slidablymounted a valve 38 comprising a valve rod 40 carrying four pistons 42,44, 46 and 48. The piston 42 is mounted at the upper end of the rod 40and is operable to engage the upper end of the casing to limit upwardmovement of the valve. Piston 48 is located near the lower end of therod and is operable to limit downward movement of the valve. The pistons44 and 46 Patented Apr. 9, 1957 are located upon opposite sides of theexhaust passage 36 and are so spaced from each other that when the valveis up fluid flows from-the source 34, through passage 32, into thecasing between pistons 46 and 48, through passage 26 into the lowerportion of the cylinder 22 thus to force the piston, spindle, and platenupwardly. At this time fluid from the upper portion of the cylinder isexhausted through passage 24, through the space between the pistons 44and 46, and out the exhaust passage 36. By this means the platen 16 isnormally maintained in position above the bed and spaced therefrom by adistance somewhat greater than the maximum height of the die used plusthe maximum thickness of the work to be operated upon.

The platen is brought down upon the work as a result of moving the valveto its lower position. When this occurs fluid passes from the source 34through passage 30, through the space between pistons 42 and 4 5,through the passage 24 into the upper portion of cylinder 22,causingdownward movement of the piston. Fluid from the lower portion ofthe cylinder fiows through passage 26, through the space between pistons44 and 46 into the exhaust passage 36.

In the preferred operation of the machine the piston 20 does not descendto the bottom of the cylinder 22 to complete its maximum stroke but isarrested and its movement reversed by moving the valve again to itsupper position as will be hereinafter described.

The valve is controlled by a solenoid 50 having a plunger 52 connectedto the lower end of the valve rod 40. When the solenoid is energized theplunger is pulled downwardly to move the valve into its lower positionresulting in downward movement of the piston and of the platen towardthe Work. When the solenoid 50 is decnergized the valve is returned toits upper position by a spring 54. When this occurs the movement of theplaten is reversed as above described.

It is to be understood-that the structure thus far described is typicaland that other means for actuating the platen, such as mechanical means,might be employed. It is highly desirable, however, that the platenactuating means be responsive to a readily controlled member such as thesolenoid here illustrated.

In the present instance it is proposed to operate the solenoid in suchmanner that the movement of the platen is reversed and the platen isthen caused to move away from the work very quickly, that is, in tenthsof seconds after the die has passed through the work and engaged thesurface layer of the cutting bed. To accomplish this the solenoid isplaced in a manually operable control circuit which is in turncontrolled bya second circuit which when closed extends through theplaten 16, die 14 and cutting bed and is activated as a result of theoperation of the platen itself.

The manually operable control circuit includes a switch 56 one side ofwhich extends through a lead 58 to an A. C. power source 60. The otherside of the switch through leads 62 and 64 extends to a coil 66 of a.relay 68 in an automatic control circuit and thence through lead 70 backto the power source. A lead 72 connects the lead 62 to one end of thesolenoid 50 the other end being connected. to a contact 74 of a relay 76also in the automatic control circuit. The relay 76 has anarmature 78normally held by a spring 79 in its illustrated position. to bridge thecontact 74 and a second contact 80 connected to the power source.

The circuit through the. solenoid is operated by a handle 82, mountedupon a pin 84 at the outer end of the platen16, and by which the platen.can. be swung about the axis of the spindle. The handle is slidablevertically of the pin and is normally held in raised position by aspring 86. The lower end of the handle is beveled at 88 and adapted to.engage, when depressed, a push button 90 for closing the switch 56. Thusdepression of. the handle 86,. at suchtime: as the relay 76 is closed,results in energization of the solenoid 50 to effect downward movementof the platen.

The automatic control circuit extends through the platen, die andcutting bed. As is customary, the platen. and die are composed of metalsuch as iron, steel or alu minum, and are therefore electricallyconductive. The bed 10, as shown in Fig. 2, comprises a plate 92 ofaluminum or other electrically conductive metal to which is bonded alayer 94 of electrically conductive rubber or plastic constituting acutting block or pad. he plate provides a still" backing for the layer94 and the layer itself provides support for the work which can readilybe penetrated by the edges of the die. As an alternative construction aWood block coated with aluminum paint has been found to be satisfactory.The cutting bed 10 rests upon a sheet" of insulating material 96, suchas fiber board, which in turn rests upon a portion 98 of the machineframe.

The automatic control circuit includes a gas tetrode tube, or thyratron100, having a control grid 102 connected through a limiting resistance104 and a lead 105 to the plate 92 of the cutting bed.

The cathode 106 is connected to one side of filament 108 and to a lead110. Another lead 112 extends from lead'l'l l'to the platen 16 and isgrounded to the frame at 114. A lead 116 extends from lead 110 to afilament current supply section 117 of the secondary 118 of atransformer 120, the primary 122 of which is connected to a 110 voltsource 124 of alternating current. The lead 195 is connected through agrid bias D. C. supply including a limiting resistor 126, lead 127,voltage dropping resistor 128 to a rectifier 130 and from thence by alead 132 to one side of a plate current supply section 1340f thetransformer secondary. The other side of the section is grounded throughlead 116. The leads 116 and 127 are connected by a voltage droppingresistor 136 and through a filter condenser 138. The plate circuitextends from the transformer section 134 through a rectifier 140 acrosscontacts 142 of the relay 68, when the armature 1'44 thereof is closed,and through a current limiting resistor 146, through a coil 148 of therelay 76, to the plate 150 of the tube 100. A filter condenser 151'connects the upper portion of the plate circuitto ground.

Bridging the relay coil 148 are a plurality of capacitors 152 eachhaving one side connected to a lead 154 extending to one end of the coil148, and the other side being connected to one of the contacts 156associated with a curved switch arm 158 joined by a lead 160 to theother end of'the coil 148. This switch arm first bridges the coil 148with one capacitor. Added movement of the arm adds more capacitors intoa parallel circuit where their capacities are added together, increasing the time required for building up the needed voltage across therelay coil 148 to operate it. The capacitors 152 constitute a time delaydevice for delaying the flow of plate current through the coil 148 andprovides selectively time-variable means by which deenergization of thesolenoid 50 is controlled. The values of the capacitors are so chosenthat a variable time delay, in operating the relay 76, of from about 5to 200 milliseconds is obtainable. For example, each capacitor may havea value of 10 microfarads.

Thus by varying time of operation of relay 76 to open the circuitthrough relay 66, the time at which the spring 54 may move the valveupwardly following engagement of the die with the cutting block, can bevaried. As a result of this, depth of penetration of the die into theblock can be controlled over a wide range.

In the operation of the machine, assuming the parts to be in theposition shown in Fig. 1, when the starting handle 82 is depressedclosing the switch 56, the coil 50 isenergized efiiecting downwardmovement of the valve 38. Fluid then flowsthrough passages 30 and 24 tothe upper portion of the cylinder 22 forcing the piston 20 get arssmoand the spindle 18 downwardly. Downward movement of the spindle causesmovement of the platen 16 down into engagement with the die 14 andforces the latter through the material 12 to produce a blank.

Upon closing switch 56 current also passes through coil 66 closing relay68 in the plate circuit. After the die passes through the material itengages the conductive upper surface of the bed bringing the gridpotential to ground or zero where the grid bias is less negative and thetube fires or becomes conductive. After a time delay of a fewmilliseconds dependent upon the capacity in the delay circuit, thevoltage builds up across the coil 148 resulting in opening the relay 76and the deenergization of the solenoid 50. When the relay opens, thespring 54 returns the valve 38 to its upper position and fluid flowsthrough passages 32 and 26 into the lower portion of the chamber forcingthe piston 20 upward with the result that the downward stroke of theplaten is arrested and then the platen is moved in a direction away fromthe bed.

As long as the handle 82 is held down relay 68 remains closed whichresults in holding the circuit through relay contacts 74, 80 open, andthe solenoid 50 remains deenergized thus preventing further operation ofthe platen. Release of the handle 82 opens the switch 56 and deenergizesthe relay 68 with the result that switch armature 144 drops, opening theplate circuit and permitting the relay 76 to close the circuit throughthe solenoid 50. After release of handle 82 the switch 56 is opened andthe parts return to the positions shown in Fig. for a subsequent cycleof operation.

From the foregoing description it will be observed that the press isprovided with a control for automatically limiting the stroke of theplaten through means responsive to engagement of the die with thecutting block and, consequently, independently of the height of the dieused. It will further be observed that the variable time delay relay forinitiating actuation of the power means in arresting the platen providesfor the control of the depth of penetration of the block by the die withthe advantages above enumerated.

It is to be understood that the press of the invention herein describedcan be employed to produce blanks from sheet material which is eitherelectrically conductive or non-conductive. When operations are to beperformed on conductive sheet material such as tin or zinc foil the timedelay is adjusted to a low value such that the mechanism for reversingmovement of the platen is operated very shortly after contact of theplaten with the die.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent of the United States is: I

1. A press comprising a work support and a platen mounted for relativemovement toward and away from each other, a cutting die located betweenthe work support and platen, means for efiecting relative movement ofthe Work support and platen toward each other in performing a pressureapplying operation of the die upon sheet material positioned upon thework support, to produce a blank, and means including an electriccircuit operative upon engagement of the die with the work support forarresting relative movement of the work support and platen toward eachother.

2. In a press having a work support and a platen arranged for movementtoward and away from the support in producing pressure applyingoperations upon a freely movable cutting die located upon sheet materialupon the support, the combination of power means for moving the platen,and means including an electric cir cuit operative upon electricalcontact of the die with the support for controlling operation of thepower means in moving the platen away from the support.

3. A machine for cutting sheet material comprising an electricallyconductive cutting block for supporting I, reset the material, a cuttingdie located with a cutting edge upon the material, power means formoving the die toward the block through the material, and meansincluding an electric circuit through the die and cutting blockoperative in response to engagement of the die with the block to reversethe movement of the power.

means.

4. A press comprising a cutting block, a freely movable die, a platenmovable toward and away from the cutting block in producing pressureapplying operations upon the die when the die is located upon sheetmaterial supported by the cutting block, means for reciprocating theplaten, means for initiating operation of the reciprocating means tomove the platen toward the block, and means including an electriccircuit through the platen, die and block operable in response toengagement of the die with the block for initiating operation of thereciprocating means to move the platen away from the block.

5. A press comprising a cutting block,'a.freely movable die, a platenmovable toward and away from the. cutting block in producing pressureapplying operations upon the die when the die is located upon sheetmaterial supported by the cutting block, means for reciprocating theplaten, means for initiating operation of the reciprocating means tomove the platen toward the block, means operable in response toengagement of the die with the block for initiating operation of thereciprocating means to move the platen away from the block, andelectrical means for selectively varying the actuation of thelastmentioned initiating means in timed relation to the engagement ofthe die with the block for controlling the extent of movement of theplaten toward the block.

6. A press comprising a work support, a die, a platen movable toward andaway from the work support in producing pressure applying operationsupon the die when the die is located upon sheet material on the worksupport, means for reciprocating the platen, means for initiatingoperation of the reciprocating means to move the platen toward the worksupport, and means including an electric circuit through the platen, dieand work support operable in response to engagement of the die with thework support for initiating operation of the reciprocating means to movethe platen away from the work support.

7. A press comprising a work support, a die, a platen movable toward andaway from the work support in producing pressure applying operationsupon the die when the die is located upon sheet material on the worksupport, means for reciprocating the platen, means for initiating.operation of the reciprocating means to move the platen toward the worksupport, electrical means operable in response to engagement of the diewith the work support for initiating operation of the reciprocatingmeans to move the platen away from the work support, and means forselectively varying the actuation of the last-mentioned initiating meansin timed relation to the engagement of the die with the work support forcontrolling the extent of movement of the platen toward the worksupport.

8. A press comprising a work support having an electrically conductivesurface portion, a die, a platen mounted for movement toward and awayfrom the work support in producing pressure applying operations upon thedie when the die is located upon sheet material on the surface portion,the die and platen being composed of electrically conductive material,power means for reciprocating the platen, manually controlled means forinitiating operation of the power means to move the platen toward thework support, means for initiating operation of the power means to movethe platen away from the work support, and means for actuating thelast-mentioned initiating means subsequently to engagement of the diewith the surface portion of the work support comprising an electriccontrol circuit through the platen, die and surface portion.

9. A press comprising a work support having an electrically conductivesurface portion; a die, a platen mounted for movement toward and awayfrom the work support'in producing pressure applying operations upon thedie when thedie is located upon sheet material on'the worksupport, thedie and platen being composedof electrically conductive material,power'means for reciprocating the platen, manually controlled means forinitiating operation of the power means to move the platen toward thework support, means for initiating operation of the power means to movethe platen away from the work support, means for actuating thelast-mentioned initiating means subsequently to engagement of the diewith the surface portion of the work support comprising an electriccontrol circuit through the platen, die and surface portion, andmeans'for selectively varying'the actuation of the last-mentionedinitiating means in timed relation to the engagement of the die with"the surface portion of the work'support.

10'. A press comprising an electrically conductive cutting block, afreely movable die, a platen mounted for movement toward and away fromthe cutting block in producing pressure applying operations upon the diewhen the die is located upon sheet material supported by the block,thedie and the platen being composed of electrically conductivematerial, power means for reciprocating the platen, manuallycontrolled'means for initiating operation of the power means to move theplaten toward the block, means for initiating operation of the powermeans to move the platen away from the block, and means for actuatingthe. last-mentioned initiating means subsequently to engagement of thedie with the block comprising an electric control circuit through theplaten, die and block.

11. A press comprising an electrically conductive cutting block, afreely movable die, a platen mounted for movement toward and away fromthe cutting block in producing pressure applying operations upon the diewhen the die is located upon sheet material supported by the block, thedie and the platen being composed of elec trically conductive material,power means for reciprocating the platen, manually controlled means forinitiating operation of the power means to move the platen toward theblock, means for initiating operation of the power means to move theplaten away from the block, means for actuating the last-mentionedinitiating means subsequently to engagement of the die with the blockcomprising an electric control circuit through the platen, die andblock, and means for selectively varying'the actuation of thelast-mentioned initiating means in timed relation to the engagement ofthe die with the block.

12. A press comprising an electrically conductive cutting block, a die,a platen mounted for-movement toward and away from the cutting block inproducing pressure applying operations upon the die when the die islocated upon sheet material supported by the block, the die and platenbeing composed of electrically conductive material, power means formoving the platen, a control element for the power means selectivelymovable into operative position to cause the power means to move theplaten toward theblock' or into'operative position to cause-the powermeans to-move'the platen away from theblock, a solenoid for moving thecontrol element into the first mentioned operative position, manuallycontrolled means for energizing the solenoid, means for deenergizing thesolenoid in response to the engagement of the die with the blockcomprising an electric circuit through the platen, die and block, andmeans for moving the control element into the second-mentioned operativeposition upon deenergization of the solenoid.

13. A press comprising an electrically conductive cutting block, a die,a platen mounted for movement toward and away from the cutting block inproducing pressure applying operations upon the die when the die islocated upon sheet material supported by the block, the die and theplaten being composed of electrically conductive material, hydraulicmeans for reciprocating the platen, a valve for controllingthe directionof movement of the platen, manually controlled' means for initiatingoperation of the valve to elfect movement of the platen towardthe'block, means for initiating operation of the valve to effectmovement of the platen away from the block, and means for actuating thelast-mentioned initiating means subsequently to engagement of the diewith the block comprising an electric control circuit through theplaten, die and block.

14. A press comprising an electrically conductive cutting block, acutting die, a platen mounted for movement toward and away fromthecutting block in producing' pressure applying operations upon the diewhen the die is located upon sheet material supported by the cuttingblock, the platen and die being composed of electrically conductivematerial, hydraulic means for reciprocating the platen, a valve for thehydraulic means selectively movable into either of two positions for controlling the direction of movement of the platen, means for moving" thevalve into position to initiate movement of the platen toward the blockincluding a solenoid, manually controlled means for initiatingenergization of the solenoid, automatic means for deenergizing thesolenoid, means including an electric circuit through the platen, dieandcutting block for initiating operation of the automatic means inresponse to engagement of the die with the cutting block subsequently topenetration of the sheet material, and means subsequently operable tomove the valve into position to initiate movement of the platen awayfrom the block;

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